The invention presented here involves a device for tensioning a tension element, preferably a chain, having a traction wheel, preferably a sprocket, rotatably mounted on a hollow axle, and having a hollow piston element arranged within the hollow axle and sprung against the hollow axle using a spring element, preferably a coil spring. The hollow piston element is arranged in a piston chamber such that the longitudinal axis of the piston element is arranged perpendicular to the traction wheel axis, and such that hydraulic fluid, preferably motor oil, arranged in the inner space of the hollow piston element, is provided for hydraulic damping of the piston element.
A device of this general type is known, for example, from the U.S. Pat. No. 5,366,417. The spring element is arranged in the aforementioned inner space for the hydraulic fluid and supported on one side, on the piston chamber, and on the other side, on a circular ring shaped disc of the piston element, which closes the inner space. At present, the parameters that are decisive for the design of this spring element can make a radially and axially enlarged construction space necessary for the spring element. In these types of cases, the known device can, under certain circumstances, no longer be applied, since with the radial enlargement of the piston, the oil throughput increases in the hydraulic part, when the inner space is used as a pressure chamber for the hydraulic fluid.